1. Field of the Invention
The present invention relates to a confined current path-current perpendicular to plane-giant magnetoresistive (hereinafter referred to as the “CCP-CPP-GMR”) head assembly which is a part having a CCP-CPP-GMR head, a magnetic recording/reproducing apparatus having such a head, and a specification method of an appropriate sense current direction of the CCP-CPP-GMR head, more particularly to the CCP-CPP-GMR head assembly in view of the prolonged operating life, a magnetic recording/reproducing apparatus having such a head, and the a specification method of an appropriate sense current direction of the CCP-CPP-GMR head.
2. Description of the Related Art
A composite head which has a reading (reproducing) head using a magnetoresistance effect (MR effect) is used in many magnetic recording/reproducing apparatuses such as magnetic disc apparatuses. A common structure of such a reading head is that a predetermined sense current (direct current) is flowing in the head and a change of a magnetic field from a medium to the head (more specifically, a written magnetic field) is recognized as a change of a voltage by the sense current. The voltage changes because a resistance changes, by the magnetoresistance effect, according to the magnetic field.
An example of a way to give the sense current to the MR head in a magnetic recording apparatus is disclosed in Japanese Patent Laid-open Application No. Hei 5-334607 (Patent document 1). In the above patent document, providing a sense current switching circuit for switching a polarity of the sense current is disclosed. It is stated that conducting switching of the polarity at any arbitrary intervals in such a structure restrains electromigration which occurs microscopically inside the head so as to prolong a head operating life. Incidentally, the head related to the above description is not a CCP-CPP-MR head or a CCP-CPP-GMR head.
[Patent document 1] Japanese Patent Laid-open Application No. Hei 5-334607 (FIG. 1, paragraph 0007, paragraph 0011, claim 12)